Jurors in a horrific, boy-toy-on-sugar-daddy castration murder heard daylong testimony by an NYPD crime scene detective who walked them through a photographic array of horror.

“Here you have a white blanket cover, and the black sneakers, and the decedent’s testicle on the white blanket,” Det. Ricardo Yanis told stunned-looking jurors, describing the blood-splattered floor of a 34th floor guest room at Times Square’s InterContinental hotel.

Inside the room, on a January evening last year, Carlos Castro — a wealthy and influential 65-year-old Portuguese fashion journalist — lay sprawled and dead, his face and groin horribly disfigured.

The floor was a tangle of bloody towels and discarded laundry, including the black Calvin Klein “extreme skinny” label jeans of Renato Seabra, 22 — the slender aspiring Portuguese fashion model who prosecutors say bludgeoned, strangled and disfigured the older man out of rage that the lucrative relationship was ending.

Defense lawyers David Touger and Rubin Sinins said the crime scene is evidence of Seabra’s insanity — as are his statements to shrinks explaining his lover’s cork-screw castration as a way of excising the “evil” and demons” within.

Seabra told shrinks he then slit his own wrists, and held Castro’s severed testicles to his bleeding arms to “harness their power.”

“What is depicted in this picture?” prosecutor Maxine Rosenthal asked the detective in walking him through the gruesome photos this morning.

“Here you can see the decedent’s other testicle,” the detective said, indicating a lump of flesh that lay on the carpeting to the side of the room’s bed, flush against the wall as if tossed there.

“What is in this picture?” Rosenthal asked as the wide-screen TV in the courtroom flickered to the next image.

“It is a corkscrew showing possible blood,” he said. In the photo, the corkscrew lay atop a white sock on the carpeting.

Some of the photos went beyond merely recording evidence, and suggest a chronology.

“This shows where the bloodstain happened,” the detective said of a photo of the bloody bottom hems of the room’s silver, floor-to-ceiling curtains.

“And then the curtain was closed.”

Hotel security video indicates Seabra had spent some five hours inside the room — amid the blood stains and broken glass and furnishings, with Castro’s uncovered, naked corpse on the floor the whole time, the face an unrecognizable crimson pulp.

The detective would later spend 13 hours inside the room, meticulously cataloguing the carnage; his testimony is expected to last throughout the day.